Exhaust/drainage mechanism

An exhaust/drainage mechanism comprising:

• a dual-purpose flow channel having:
• an upper part through which contaminated air discharged from a coating booth together with non-attached paint flows;
• a lower part through which contaminated water discharged from the coating booth together with non-attached paint flows;
• a first flow channel extending along one side surface of the coating booth;
• a second flow channel extending orthogonally to the first flow channel and horizontally from one end part on a downstream side of the first flow channel;
• an extended part that is (i) on a downstream side of a passing part of the dual-purpose flow channel, (ii) located at a middle of the dual-purpose flow channel, (iii) wider than the passing part, and (iv) configured to generate an upper-layer swirling flow by swirling the contaminated water flowing from the passing part;
• an internal protruding wall (i) protruding in an extending direction of the first flow channel from an inner side corner formed between the first flow channel and the second flow channel and (ii) narrowing the passing part from the first flow channel to the extended part;
• a first inner side surface (i) opposing the internal protruding wall so as to interpose the passing part between the first inner side surface and the internal protruding wall and (ii) guiding the contaminated air and the contaminated water flowing in the first flow channel toward the extended part;
• a second inner side surface opposing the first inner side surface so that the extended part is interposed between the second inner side surface and the first inner side surface in the second flow channel;
• and
• a third inner side surface connected to the second inner side surface and opposing a separation wall from an upper-stream side of the second flow channel;
• a dust separator having a suction port disposed above the extended part, the dust separator configured to (i) suck the contaminated air upward from the suction port, (ii) centrifugally separate dust, and (iii) drop the centrifugally-separated dust in the contaminated water in the dual-purpose flow channel;
• a storage chamber on a downstream side of the extended part and separated from the extended part by the separation wall, the separation wall (i) being provided in a middle part in a longitudinal direction of the second flow channel and (ii) separating the dual-purpose flow channel on a side above the contaminated water into the extended part and the storage chamber;
• a scum receiving inlet provided in the separation wall to take into the storage chamber floating coating scum floating on the contaminated water;
• a suction pipe which is opened upward in a vicinity of a surface of the contaminated water in the storage chamber and into which the floating coating scum flows;
• and
• a contaminated water guide (i) disposed at the extended part, (ii) having a plate shape partly submerged in the contaminated water, and (iii) extending linearly in a radial direction from a center of the upper-layer swirling flow to a corner portion between the separation wall and the second inner side surface to guide the floating coating scum together with a surface layer portion of the contaminated water into the scum receiving inlet.